JPH03274165A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To discharge ink always stably by removing small bubbles certainly even when small bubbles are generated in a liquid path of a recording head by a method wherein the title ink jet recorder is so constructed that running of recording liquid and discharge of a liquid drop are simultaneously carried out. CONSTITUTION:When recording is performed, a solenoid valve 62 is kept in an open condition, and recording liquid in a supply tank 55 is supplied to a common liquid chamber 108 by its dead weight to be conducted to a discharge opening 111 through a liquid path. Further, in recovery operation to be executed in order to remove foreign matters such as bubbles or the like remaining in a common liquid chamber 108 and a supply system and to cool a recording head 1, all discharge openings 111 are sealed by covering a discharge opening surface 54 with a cap, and ink is sent into a common liquid chamber 108 with a circulating pipe 61 by driving a pump 59 by opening a recovering rectifying valve 60. Besides, bubbles as well as ink are pushed out from the discharge opening 111 by driving the recording head 1, and the ink in the common liquid chamber 108 is further circulated to the supply tank 55 through a first ink supply pipe 107.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an ejection recovery system in an inkjet recording apparatus.

[Prior Art] Recording devices such as printers, copying machines, and facsimiles are configured to form images consisting of dot patterns on recording materials such as paper and thin plastic plates based on recorded information. .

The recording device may be an inkjet type,
It can be divided into wire dot type, thermal type, laser beam type, etc. Among them, inkjet type (inkgeno 1-recording device) ejects small droplets of recording liquid (hereinafter also referred to as ink) from the ejection opening of the recording head. It is configured so that it can be made to fly and be attached to a recording material such as paper or a thin plastic plate for recording.

An example of the configuration of a conventional ink side recording apparatus is disclosed in Japanese Patent Application Laid-Open No. 60-247564 by the same applicant.

This inkjet recording apparatus provides an opening/closing means (valve, etc.) and a pump in the middle of an ink supply path connecting a recording head and an ink tank, and appropriately switches the opening/closing state of the opening/closing means and the operating state of the pump. In addition to the print mode that performs printing, there is also a pressurization mode that removes clogging in the liquid path (liquid flow path that passes through the ejection ports) of the print head, or a circulation mode that removes air bubbles in the ink supply path. It is configured so that the mode etc. can be set.

FIG. 8 is a block diagram schematically showing the configuration of an ink supply system of such an inkjet recording apparatus.

In FIG. 8, this ink supply system includes an on-off valve 150, a ventilation on-off valve 152, and an on-off valve 154, depending on the operation mode such as recording mode, circulation mode, and pressurization mode.
and controls the operation of the pump 156 to form an appropriate ink flow path between the first ink tank 130 and the second ink tank 140 and the recording head 174 (in the illustrated example, a plurality of recording heads). It is composed of

The operation of each on-off valve and pump in each of the operation modes is as shown in Table 1.

FIG. 9 is a cross-sectional view schematically showing a state in which the circulation mode or the pressurization mode is operated to cause ink to flow in the recording head 174 in FIG. 8.

Inside the recording head 174, as shown in the figure, a plurality of liquid channels 21 are formed which pass through a common liquid chamber 28. A plurality of discharge ports 24 are formed by opening them as openings.

Note that 25 indicates small bubbles (small bubbles) generated within the liquid path 21.

Table 1 [Technical Problems to be Solved by the Invention] However, in the above-mentioned conventional inkjet recording apparatus, in order to remove the small bubbles 25 remaining in the liquid path 21, the recording
Even if the ink 22 in 74 is made to flow in the direction of arrow 23, the ink 22 passes through in the direction of arrow 26 in the liquid path 21 and the small bubbles 25 are not pushed out from the discharge port 24. was there.

Therefore, the small bubbles sometimes caused non-discharge.

The present invention has been made in view of such conventional technical problems, and even if small bubbles occur in the liquid path of the recording head, they can be reliably removed, and stable ink can be produced at all times. An object of the present invention is to provide an inkjet recording device that can perform ejection.

[Means for solving problems]

The present invention provides an inkjet recording apparatus that includes a recording head that discharges droplets using thermal energy, and a flow means that causes the recording liquid in the recording head to flow, in which the droplets are discharged simultaneously with the flow of the recording liquid. By adopting such a configuration, even if small bubbles are generated in a liquid path of a recording head, the inkjet recording device can surely remove the bubbles and always perform stable ink discharge.

5 Examples: Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 2 is a schematic side view showing an embodiment of an ink jet recording apparatus according to the present invention.

In FIG. 2, lBk, ly, 1m, and lc are recording heads (for example, bubble jet inkjet heads) corresponding to black, yellow, magenta, and cyan ink colors, respectively, and have built-in ejection energy generators ( Ink droplets (recording droplets) are ejected from an ejection port using air bubbles generated in ink when electricity is applied to a heating resistor, etc. as a pressure source.

That is, these recording heads IBk, 1y, 1m, 1
In c, a droplet is ejected from an ejection port using thermal energy, and the droplet is attached to a recording material such as a sheet of paper or a thin plastic plate for recording.

These recording heads IBk, ly, 1m, and lc are fixed to block 2.

Each recording head I has, for example, 4736 ejection ports arranged at a density of 400 dpi.

Reference numeral 3 designates a camping unit, which when the block 2 is pulled up to the position indicated by the dotted chain line in FIG. It is used for capping (sealing).

The camping unit 3 also has a receiver for receiving a portion (waste ink) of the ink that has been circulated into the recording head 1 from a recovery pump (not shown) and an ink supply system that has been pushed out from the ejection ports during circulation recovery. It becomes a plate.

The received waste ink is led to a waste ink tank (not shown).

4 is arranged to face the recording heads IBk, 1y, III, and IC at a predetermined interval, and has an endless charged adsorption belt for conveying the recording material 7 such as recording paper or plastic sheeting board. 5 is a hack platen that supports the charging/adsorption belt 4 from the back surface in the areas of each recording head 1Bk, ly, 1m, and 1c.

Reference numeral 6 denotes a paper feed cassette that stores the recording material 7 and is detachably attached to the main body of the apparatus, and 8 indicates the recording material 7 on the uppermost surface.
This is a pink-up roller that feeds only one sheet of paper.

9 is a conveyance roller that conveys the recording material 7 sent out from the pickup roller 8 to the conveyance path 10;
is a conveyance roller disposed on the exit side of the conveyance path 10.

Reference numerals 13 and 14 indicate a heater and a fan that dry and fix the ink liquid attached to the recording material 7 due to recording using hot air, and 15 indicates an ejection roller that discharges the recording material 7 out of the apparatus after fixing. Reference numeral 16 denotes a tray for sequentially stocking the discharged recording materials 7.

Next, the operation of the inkjet recording apparatus having the above configuration will be explained.

First, the recording operation will be explained.

When an operation to start recording is performed, a recording material 7 of a specified size is sent out from the paper feed cassette 6 by a pick-up roller 8.

The fed-out recording material 7 is transferred to bill feeding rollers 9 and 11.
As a result, the belt travels in a pre-charged state and is placed on the '41'H suction belt 4 which is maintained in a flat shape by the hack platen 5.

The leading end of the recording material 7 is the recording head IBk, 1y, 1+l
, in conjunction with reaching the bottom of each of the ICs.
The thermal energy generator of each recording head is driven based on the image data via the gutter drive circuit.

By this driving, ink droplets corresponding to the image information are ejected from the ejection ports onto the recording surface of the recording material 7, and are attached thereto to perform recording.

If the hygroscopicity of the recording material 7 is poor (low), the attached ink liquid will rub without drying and cause image stains.
Forced drying is performed using a heater 13 and a fan 14 to fix the image.

The recording material 7 that has been fixed is discharged onto a tray 16 by a discharge roller 15.

As described above, each recording corresponds to each ink color of Noan, magenta, 1' yellow, and blank.

A color image is recorded by applying recording signals corresponding to the IBk, 1y, 1m, and 1c, respectively.

Next, the ejection principle of the recording head 1 used in the ink side recording apparatus shown in FIG. 2 will be explained.

The recording head (inkjet head) of an inkjet recording device generally includes fine ejection ports formed on the ejection port surface (front surface) facing the recording material 7, a liquid flow path passing through each ejection port, and a liquid flow path that passes through each ejection port. An energy acting section provided in a part of the liquid flow path and an energy generating means that acts on the liquid (ink) in contact with the acting section to form and eject droplets are provided.

Energy generating means for generating such energy include recording methods using electromechanical transducers such as piezo elements, irradiating electromagnetic waves such as lasers, absorbing them into the liquid, and causing the liquid to generate heat due to the heat generated at that time. There are recording methods using energy generating means for ejecting and flying droplets, and recording methods using energy generating means for ejecting liquid by heating the liquid with an electrothermal converter.

Among these, the recording head used for the inkjet recording method, which discharges liquid using thermal energy, has a high density arrangement of tl for recording and discharge ports for discharging droplets to form flying droplets. , it is possible to perform high-resolution recording.

Furthermore, a recording head that uses an electrothermal converter as an energy generating means can be easily made compact overall, and it also uses IC technology and microfabrication technology, which have undergone remarkable technological advances and improved reliability in the semiconductor field in recent years. Since it is easy to make the length and planar (two-dimensional), it is easy to have multiple discharge ports and high-density packaging, and it is also easy to mass-produce. It is possible to provide an inkjet recording head that has excellent properties and is inexpensive to manufacture.

As shown in item 2, inkjet recording nozzles that use an electrothermal converter as an energy generating means and are manufactured through a semiconductor manufacturing process, are generally provided with a plurality of liquid channels corresponding to each ejection port. By applying thermal energy to the liquid filling each liquid flow path,
An electrothermal converter is provided as a means for ejecting liquid from the corresponding ejection port to form flying droplets, and each liquid flow path is supplied with liquid from a common liquid chamber communicating with each liquid flow path. The supplied structure is adopted.

FIG. 3 is a partially cutaway perspective view schematically showing the general structure of the above-mentioned inkjet recording head. The electrothermal converter 103 and the electrode 104 formed on the bottom film 102 and the liquid path 1
10, etc., and a top plate 106.

Recording liquid (ink) 112 is supplied to recording through an ink supply pipe 107 from a liquid storage chamber (not shown).

The liquid is supplied into the common liquid chamber 108 of the door 101.

In FIG. 3, 109 is an ink supply pipe connector.

The ink 112 supplied into the common liquid chamber 108 is supplied into the liquid path 110 by capillary action, and is stably held by forming a meniscus at the discharge port 111 at the tip of the liquid path 110.

Here, by supplying electricity to the electrothermal converter 103, the liquid on the surface of the electrothermal converter 103 is heated, a bubbling phenomenon occurs, and droplets are ejected from the ejection port 111 by the energy of the bubbling.

With the above configuration, a multi-type inkjet recording head can be constructed with a high-density ejection port arrangement such as an ejection port density of 400 DPI.

FIG. 1 is a schematic diagram showing an ink supply system for the recording head 1 of FIG. 2. FIG.

In FIG. 1, 1 is a recording head, 54 is an ejection port surface (the front surface where ejection ports are formed), 111 is an ejection port for ejecting ink arranged on the ejection port surface, and 112 is a common chamber. .

The ejection ports 111 are arranged at a predetermined pinch (density) like the recordable width of the target recording material 7 (FIG. 2). ) is provided with an electrothermal converter (heating element) 103 (FIG. 3) that generates discharged thermal energy.

Additionally, these liquid paths 110 are connected to the common liquid chamber 108.
I'm passing through.

Therefore, by selectively driving the electrothermal transducer 103, the configuration is such that printing can be performed without main scanning of the print head 1 itself.

The recording head has, for example, a total of 4,736 ejection ports formed at a density of 400 DPI (dots/inch), and is therefore a high-density, wide-width multi-metal printer that can record the vertical width of a standard A3 size at one time. It is made up of.

Each liquid path (not shown) passing from the common liquid chamber 52 to the individual ejection ports 53 is provided with a heating element that generates ejection energy, and the heating element is selectively driven based on recorded information. As a result, the recording droplets are ejected and fly to record an image on the recording material.

In this case, printing can be performed without main scanning of the print head 1 itself.

In FIG. 1, 55 is an ink supply tank for supplying ink (recording liquid) to the recording head 1, 56 is a main tank for replenishing the supply tank 55 with ink,
Ink in the supply tank 55 is supplied to the common liquid chamber 10 of the recording head 1 through the ink supply pipe 107.

Further, the supply tank 55 is replenished with ink by a pump 59 from the main tank 56 via a one-way replenishment rectifier valve 58.

Reference numeral 60 indicates a one-way recovery rectifier valve used during a recovery operation to recover the ejection function of the recording head 1, and 61 indicates a circulation pipe in which the recovery rectifier valve 60 is installed.

Further, 62 indicates a solenoid valve installed in the supply pipe 107, and 63 indicates an air vent valve of the supply tank 55.

For recording configured in this way, when recording in the ink supply system and recovery system of the dome 1, the solenoid valve 62 is
is kept open and the record in the supply tank 55!
(ink) is replenished into the common liquid chamber 108 by its own weight, and the recording liquid in the common liquid chamber 10B is guided to the ejection port 111 through a liquid path (not shown).

In addition, during the recovery operation performed to remove foreign substances such as air bubbles remaining in the common liquid chamber 108 and the supply system and to cool the recording head l, the ejection port surface 54 is covered with a cap (not shown). All discharge ports 111 are sealed,
By opening the recovery rectifier valve 60 and driving the pump 59, ink is sent into the common liquid chamber 108 through the circulation pipe 61, and at the same time, the recording head 1 is driven to push out air bubbles together with the ink from the ejection port 111, and the common liquid chamber 108 is driven. Liquid chamber 108
The ink inside is further circulated to the supply tank 55 through the first ink supply pipe 107.

Furthermore, when initially filling the liquid path 110 of each discharge port 111 with ink, the solenoid valve 62 is closed, the recovery pump 59 is driven, and the ink is forcefully fed into the common room 52 through the circulation pipe 61. However, bubbles and the like can be ejected from the ejection port 53 along with the ink.

FIG. 4 shows the recovery pump 59 during the aforementioned recovery operation in the inkjet recording apparatus explained in FIGS. 1 to 3 above.
2 is a graph showing an example of the timing of driving of the recording head 1 and the driving of the recording head 1.

That is, in this embodiment, when the recovery pump 59 is driven in the recovery operation, at the same time, the electrothermal transducer 103 (FIG. 3) in each liquid path 110 of the recording head 1 is driven to transfer ink to each ink. It is configured to be discharged from a discharge port 111.

5 and 6 are cross-sectional views schematically showing the state of bubble removal in the liquid path 110 when driving as shown in FIG. 4 is performed.

As shown in FIG. 4, when the recovery pump 59 is driven, the recording head 1 is simultaneously driven to eject ink from each ejection port 111, as shown in FIG. Small bubbles (small bubbles) 25 (
9) are combined (or absorbed), and as shown in FIG. 6, as the ink flows out from the passageway 110 in the direction of the arrow 32, the combined bubbles 31 are pushed out from the ejection port 111, and the small bubbles 31 are pushed out from the ejection port 111. 25 is removed.

As described above, in an inkjet recording apparatus equipped with a recording nozzle 1 for ejecting droplets absorbed by thermal energy and a flow means 59 for causing the recording liquid in the recording head 1 to flow, the liquid flows simultaneously with the flow of the recording liquid. An inkjet recording device configured to eject droplets can reliably remove small bubbles 25 even if they occur in the liquid path 110 of the recording head 1, and can always perform stable ink ejection. was gotten.

FIG. 7 shows the driving of the recovery pump 59 and the recording head 1 in another embodiment of the inkjet recording apparatus according to the present invention.
FIG. 2 is a timing chart showing the driving relationship of FIG.

In the embodiment shown in FIG. 4, a case is shown in which the drive of the recovery pump 59 and the drive of the recording head 1 are completely matched from the start time to the end time, but when implementing the present invention, it is not always necessary to completely match the drive in this way. It is not necessary to do this, and as shown in FIG. 7, drive timing may be adopted to maintain simultaneity, such as driving one drive as appropriate within the drive time of the other.

Furthermore, the driving of the recording head 1 is not limited to the same driving conditions as during recording, but may be performed under different driving conditions, such as increasing or decreasing the driving pulse width as appropriate, or dividing the driving pulse to give small bubbles. Various conditions can be set as long as the driving conditions are such that the bubbles that take in (combine) the bubbles can be formed.

INDUSTRIAL APPLICATION This invention brings about the outstanding effect especially in the printing head and printing apparatus of the Hubble Jet printing method among the inkjet printing methods.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796.

This method can be applied to both the so-called on-demand type and continuous type, but in the case of the on-demand type, it is especially important to apply it to the sheet or liquid path where liquid (ink) is held. By applying at least one drive signal that corresponds to recorded information and causes a rapid temperature rise exceeding nucleate boiling to the disposed electrothermal transducer, the electrothermal transducer is caused to generate thermal energy, and the recording is performed. fart,
This method is effective because it causes film boiling on the heat-active surface of the liquid (ink), resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal.

Due to the growth and contraction of these bubbles, liquid (
ink) to form at least one droplet.

If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately, so liquids with particularly excellent responsiveness (
This method is more preferable since it is possible to eject ink (ink). As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable.

Further, if the conditions described in US Pat. No. 4,313,124 concerning the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be achieved.

The configuration of the recording head includes, in addition to the combined configuration of ejection ports, liquid paths, and electrothermal converters (straight 'a, flow path, or right-angled liquid flow path) as disclosed in the above-mentioned specifications. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,596 disclose a configuration in which the action portion is arranged in a bending region.
A configuration using the specification of No. 00 is also included in the present invention.

In addition, Japanese Patent Application Laid-open No. 123670 of 1982 discloses a configuration in which a common slit is used as a discharge part for a plurality of electrothermal converters, and a hole that absorbs pressure waves of thermal energy is disclosed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 138461 of 1981, which discloses a configuration in which a discharge portion corresponds to a discharge portion.

Furthermore, as a full-line type recording gutter having a length corresponding to the width of the maximum recording medium that can be recorded by the recording device, the length can be increased by combining multiple recording heads as disclosed in the above-mentioned specification. Either a configuration that satisfies the above requirements or a configuration as a single recording head formed integrally may be used, but the present invention can more effectively exhibit the above-mentioned effects.

In addition, by being installed in the device main body, it is possible to make an electrical connection with the device main body and supply ink from the device main body. The present invention is also effective when using a cartridge type recording head.

Further, it is preferable to add recovery means, preliminary auxiliary means, etc. for the recording head, which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized.

Please list these specifically.+i For the recording head,
Camping means, cleaning means, pressurizing or suction means, an electrothermal converter or a separate heating element, or a combination thereof (2) Unbalanced heating means, preliminary ejection for recording and other ejection. Performing mote is also effective for stable recording.

Furthermore, the recording mode of the recording device is not only a recording mode of only mainstream colors such as different colors, but also a recording head of two or more integrated configurations or a combination of two or more, but it is also possible to use multiple colors of different colors or mixed colors. The present invention is also extremely effective for devices equipped with at least one full color image.

E. Effects of the Invention: As is clear from the above description, according to the present invention, an inkjet printer is provided which includes a recording head that ejects droplets using thermal energy and a fluidizing means that causes the recording liquid in the recording head to flow. Since the recording apparatus is configured to eject the droplets at the same time as the recording liquid flows, even if small bubbles form in the liquid path of the recording throat, they can be reliably removed and can be constantly An inkjet recording apparatus capable of stably ejecting ink is provided.

[Brief explanation of drawings]

FIG. 1: A schematic diagram showing an ink supply system of an inkjet recording device according to the present invention S2, FIG. 2 a side view schematically showing an embodiment of an inkjet recording device according to the present invention, and FIG. FIG. 4 is a partially cutaway perspective view schematically showing the recording head in FIG. 2, FIG. 4 is a timing chart showing the drive of the recovery pump and recording head of the 1' jet recording apparatus according to the present invention, and FIG. FIG. 6 is a vertical cross-sectional view schematically showing the state of the liquid path of the recording nozzle driven based on the drive start time; FIG. 6 is a vertical cross-sectional view schematically showing the state after a predetermined time has elapsed from FIG. FIG. 7 is a timing chart showing another drive of the recovery pump and the print head of the inkjet printing apparatus according to the present invention, FIG. 8 is a schematic diagram showing the ink supply system of a conventional inkjet printing apparatus, and FIG. 9 is a conventional ink supply system. FIG. 2 is a vertical cross-sectional view schematically showing the ink flow state of the liquid path of the recording head of the inkjet recording apparatus. Below, symbols representing main components in the drawings are listed. Recording - throat capping 5 - small bubbles, 31 ink supply 58 rectifier valve, 61 103 aether heat conversion 107 ink supply 110 - M path, l recording liquid (ink). 1, IBk, ly, 1m, lc (inkjet head), 3 units, 4-land transport belt, tens, 7-recording material, 25 air bubbles, 54--discharge port surface, 55 ink, 56--main Tank, 59 Recovery pump, 60 Circulation pipe, 62 - Solenoid valve, Body (thermal energy generator), Supply pipe, l O8 - Common liquid chamber, 11 - - Discharge port, 112

Claims (1)

[Claims] (1) In an inkjet recording apparatus equipped with a recording head that discharges droplets using thermal energy and a flow means that causes the recording liquid in the recording head to flow, the droplets are discharged at the same time as the recording liquid flows. An inkjet recording device characterized by: